1. Field
Communication systems, such as reliant on the third generation partnership project, may benefit from a reduced number of discontinuous reception cycles needed to receive emergency messages. More specifically, such communication systems may benefit from methods and systems for sending broadcast control channel modification info/earthquake and tsunami warning system information to user equipment in enhanced cell paging channel in one discontinuous reception cycle.
2. Description of the Related Art
According to third generation partnership project (3GPP) prior to release 7 (Rel-7), a user equipment (UE) in idle mode, and in universal terrestrial radio access (UTRA) registration area (URA)/cell paging channel (PCH) state can be informed about broadcast type of information. This broadcast type of information include, for example, broadcast control channel (BCCH) modification info information element (IE) through PAGING TYPE 1, paging control channel (PCCH)/PCH/secondary-common control physical channel (S-CCPCH). In order for all user equipment to get this information, radio resource control (RRC) message PAGING TYPE 1 is repeated over 1 discontinuous reception (DRX) cycle.
UEs in the cell forward access channel (FACH) receive BCCH modification info through RRC message SYSTEM INFORMATION CHANGE INDICATION (BCCH/FACH/S-CCPCH).
In 3GPP Rel-7, enhanced cell FACH, and enhanced Cell PCH are introduced, and the BCCH modification info IE is sent to UEs having high speed downlink shared channel (HS-DSCH) reception capabilities in cell FACH, and in cell PCH, through different transport channel, HS-DSCH, and physical channel, high speed physical downlink shared channel (HS-PDSCH).
This increases the combinations in which the BCCH modification info is sent to UEs in cell, due to cells having different configurations, such as enhanced Cell FACH and enhanced Cell PCH.
For example, BCCH modification info is sent in RRC message PAGING TYPE 1 through PCCH/HS-DSCH/HS-PDSCH to those UEs, which have HS-DSCH reception capability in URA PCH state, and in Cell PCH state, but have not been assigned dedicated high speed downlink packet access (HSDPA) radio network temporary identifier (H-RNTI).
The RRC message PAGING TYPE 1 is repeated over one DRX cycle so that all the UEs having no dedicated H-RNTI receive this message.
The UEs, that have HS-DSCH reception capability in Cell PCH states and are assigned dedicated H-RNTI, receive BCCH modification info IE in RRC message SYSTEM INFORMATION CHANGE INDICATION.
This RRC message is also repeated for one DRX cycle, so that all the UEs having dedicated H-RNTI receive the message. Thus, it can take two DRX cycles to get the BCCH modification info IE to all the UEs that have HS-DSCH reception capability in URA PCH and in Cell PCH, because SYSTEM INFORMATION CHANGE INDICATION and PAGING TYPE 1 are not sent together on HS-DSCH.
Furthermore, an earthquake and tsunami warning service (ETWS) information IE is introduced in 3GPP release 8, and this IE is sent to UEs in the same RRC messages that are used to carry BCCH Modification info IE. This means that it will take two DRX cycles to get ETWS Information IE to all the UEs that have HS-DSCH reception capability in URA PCH and in Cell PCH. ETWS information is emergency type of broadcast, which has the highest priority, and 3GPP has set a time requirement so that ETWS information should reach to UEs in notification area, from private land mobile network (PLMN) in 4 seconds. This path can include cell broadcast center, to radio network controller/base transceiver station to user equipment.
Whenever earthquake and Tsunami warning needs to be sent to UEs in the notification area (notification area could cover one cell or more than one cells), UTRAN is required to generate and process multiple messages, as captured in Table 1, simultaneously, to meet the time requirement of 4 seconds. As can be seen from Table 1, there are so many messages which need to be processed by RNC, and Node B at the same time in order to meet the timing requirement. In this situation of urgency, when ETWS Information IE is sent to all UEs in cell (neither enhanced cell FACH, nor enhanced Cell PCH configured in the cell) through RRC message PAGING TYPE 1 (PCCH/PCH/S-CCPCH) over 1 DRX cycle.
On other hand, it takes 2 DRX cycles to transmit the ETWS Information IE to all the UEs in URA/Cell PCH having HS-DSCH reception capability, as explained above. This leaves total time budget of 2.72 seconds [4 seconds−1.28 seconds (assuming DRX cycle default=64 frames=640 ms=0.64 seconds)=2.72 seconds] to process ETWS information from CBC→RNC, to process 128 frames (2×64) at RNC, to transport 128 frames from RNC to node B or base transceiver station (BTS), to process 128 frames at node B/BTS, and UEs receive ETWS information, and either display the warning on the screen, vibrate the UE, or make a distinct sound.
The following Table 1 consists of messages that are sent from the RNC during the broadcast of ETWS related information to all the UEs in the notification area. Thus, Table 1 shows the complexity of this emergency procedure.
TABLE 1UEs having HS-DSCHlub Commonreception capabilityLogical channel/Transportin Cell FACH & URA/CellRRC MessageTransport Channel/Channel DataPCH (Yes/No)UE RRC StateRRC Message(sent/repeated)Physical ChannelFrameBCCHNoIdle mode, CellPAGING TYPE 1Repeated over 1PCCH/PCH/PCH DATAModificationPCH,DRX CycleS-CCPCHFRAMEinfo IE/URA PCHETWSYesURA/Cell PCH (noPAGING TYPE 1Repeated over 1PCCH/HS-HS-DSCHInformationdedicated H-RNTIDRX CYCLEDSCH/HS-FRAME TYPEIEassigned to UE.)PDSCH3YesCell PCHSYSTEMRepeated over 1BCCH/HS-HS-DSCH(dedicated H-RNTIINFORMATIONDRX CYCLEDSCH/HS-FRAME TYPEassigned to UE.)CHANGEPDSCH3INDICATIONNo.Cell FACHSYSTEMSent at leastBCCH/FACH/FACH DATAINFORMATIONONCES-SCCPCHFRAMECHANGEINDICATIONYesCell FACH (with orSYSTEMSent at leastBCCH/HS-HS-DSCHwithout dedicatedINFORMATIONONCE/DRXDSCH/HS-FRAME TYPEH-RTI)CHANGECycle (if enhancedPDSCH2INDICATIONUE DRX in CellFACH feature isconfigured in thecell)
Further to the above, the UE may receive the ETWS PRIMARY NOTIFICATION WITH SECURITY message via dedicated control channel (DCCH), when the UE is in a state where it is configured to receive DCCH.